Wednesday, May 31, 2017

‘We have been poisoning ourselves’: has ice analysis revealed the truth about lead?
Exclusive: ice cores and records from the Black Death show lead entered the air from human activity – and scientists claim “natural background” levels are zero

The ice core, extracted from a glacier in the Swiss-Italian Alps. Photograph: Nicole SpauldingNicola Davis
@NicolaKSDavis

Analysis of an ice cores taken from the Swiss Alps together with records dating from the time of the Black Death have revealed that there is no “natural” level of lead in the air, researchers have claimed.

Once in the body, lead is known to have harmful impacts on health, from behavioural to neurological, reproductive and cardiovascular effects.

With events such as volcanic eruptions releasing lead into the air, it was thought that even before industrial times there was a “natural background” level.

But now researchers say that level has been overestimated, finding that traces of lead trapped within the ice core fell to undetectable levels as the Black Death swept across medieval Europe, shutting down industry and killing more than a third of the continent’s population.

“We have for the first time a lead reading of what it would look like without humans on this part of the planet,” added Chris Loveluck, an archaeologist from the University of Nottingham and co-author of the research.

The findings suggest that even before the industrial revolution, atmospheric lead was primarily a result of human activity. As a result, they add, there is no “safe” background level of lead pollution.

“We have basically been poisoning ourselves for about 2,000 years,” said Alex More, a historian and climate scientist at Harvard University and another author of the study...